Process for treating sucrose-bearing fibrous materials



March 19, 1968 A. w. FRENCH PROCESS FOR TREATING SUCROSE-BEARING FIBROUS MATERIALS Filed Sept. 27, 1965 INVENTOR. ALFRED W. FRENCH BY W ATTORNEY 3,373,679 PROCESS FOR TREATING SUCRGSE- BEARING FIBROUS MATERIALS Alfred W. French, Piqua, Ohio, assignnr to The French Oil Mill Machinery Company, Piqua, Ohio, at corporation of Ohio Filed Sept. 27, 1965, Ser. No. 490,329 4 Claims. (Cl. 100-37) ABSTRACT OF THE DISCLOSURE Sugar cane material, raw cane or bagasse, is processed through a rolling mill or shredder to rupture the cells and expose the fibers, and then conveyed to a mechanical press having substantial drainageopenings and capable of sustaining pressure on the material. Hot fluid such as steam is added to the material during the time it is being conveyed to increase its temperature to at least 160 F. and preferably to within a range of 180 F. to 200 F. The heated material is fed directly into the press and liquid is expressed from the material with substantially reduced power required to drive the press.

This invention relates to the treatment of sugar-bearing fibrous material, and more particularly to an improved process for mechanically expressing liquid from sugar cane or sugar cane bagasse, or the like within a mechanical screw press whereby substantially less power is required for operating the press thus providing for more efiicient operation and a reduction of wear of the press components.

When a mechanical screw press is used for dewatering sugar cane bagasse, the bagasse is commonly fed by a conveyor from machinery where sucrose bearing juice is removed, such as from a roller mill or a diffuser, to the inlet of the screw press. One arrangement for pressing bagasse from a roller mill is disclosed in US. Patent No. 3,086,452, issued to the assignee of this application. When the bagasse is fed into the screw press in such a system, it is at a relatively low temperature, in the order of 120 F. or less, especially when the bagasse is received at the inlet of the press from a roller mill. As a result of the tough fibrous texture of this low temperature bagasse, substantialrpower is required to rotate the main screw for feeding the bagasse through the press. It has been found, however, that when the bagasse is heated immediately before it is fed into the press, there is a substantial drop in the power required to drive the press, although the same capacity through the press is achieved.

Accordingly it is a primary object of the present invention to provide an improved process for removing liquid which is primarily water with dissolved sucrose from sugar cane or from sugar cane bagasse within a mechanical screw press so that the power requirements for operating the press are minimized.

As another object, the present invention provides a process for treating sugar cane or sugar cane bagasse wherein the cane or bagasse is conveyed from machinery where the cane is ground or where sucrose bearing juice is removed to the inlet of a mechanical screw press and is heated while being conveyed such that relatively hot bagasse is fed into the press causing the bagasse to be more easily fed through the press.

Still another object of the invention is to provide a process as outlined above wherein steam is introduced into the cane or bagasse before it enters the inlet of the screw press thereby adding heat to the bagasse tending to soften its fibers and making it easier to work within the press.

States Patent Ofiice 3,373,79 Patented Mar. 19, 1968 It is also an object of the invention to provide a process asoutlined above wherein the cane or bagasse is conveyed from a final stage rolling mill where the sucrose bearing juice is removed to the inlet of a high pressure mechanical screw press by a continuous conveyor into which steam is introduced for increasing the temperature of the bagasse in excess of 160' F. and preferably within a range of 180 F. to 200 F. so that the bagasse can be processed within the press with substantially less horsepower required for driving the press while maintaining the desired capacity of the press.

It is also an object of the invention to provide a process as outlined above wherein steam is applied to the bagasse received from a diffuser and being fed into a screw press so that the temperature of the bagasse as it enters the screw press will be upwards of 160 F.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawing and the appended claims.

In the drawing- FIG. 1 is a schematic diagram of an apparatus and process as constructed and performed in accordance with the invention;

FIG. 2 is a fragmentary schematic diagram illustrating the use of the invention with a diffuser;

FIG. 3 is a cross-sectional view through the screw press shown in FIG. 1, taken along the line 3-3; and

FIG. 4 shows the invention as applied to sugar cane which has been passed through a grinder, such as a hammermill.

Referring to the drawing which illustrates preferred embodiments of the invention, the system shown schematically in FIG. 1 includes apparatus as disclosed in applicants aforementioned US. Patent No. 3,086,452 for processing sugar cane to extract sucrose bearing juices. An endless conveyor 10 delivers the sugar cane C to a crushing apparatus 12 comprising a pair of crushing rolls 14 which have suitably formed working surfaces for crushing'and breaking the cane and deliver the cane onto a conveyor 16. The initial sucrose-bearing juice, which is removed by crushing the cane between the rolls 14, is collected within a suitable receptacle 18 for subsequent processing, along with the juice extracted at later stages, in conventional sucrose extraction equipment.

The crushed cane is fed by the conveyors 16 and 19 into one or a series of successively spaced roller type mills 20 which are commonly used to extract from the cane additional sucrose-bearing juices which are collected within the tank 22. To increase the extraction of juices from the sugar cane by the roller mills 20, preferably maceration fluid is sprayed onto the bagasse from the supply lines 23 between separate stages of milling.

The bagasse which is delivered onto the conveyor 24 from the final roller mill 20 will commonly have between and of the sucrose removed by the action of the crushing rolls 14 and the roller mills 20. Furthermore, by the time the bagasse is discharged onto the conveyor 24, although it may become heated somewhat during milling, it rarely exceeds a temperature of B As illustrated in FIG. 1, the bagasse delivered by the conveyor 24 is discharged into the inlet 26 of a conveyor 28 comprising an elongated tubular housing 29. As shown,

the conveyor 28 is of the screw type and thus has a continuous feed screw 30 rotatably mounted within the housing 29 and is driven by a variable speed drive unit 32. As the bagasse is fed from the inlet 26 of the conveyor 28 to its outlet 34 by the rotation of the conveyor screw 30, the bagasse is heated along the conveyor, preferably by introducing steam into the housing 29 through a connecting manifold 36. It is to be understood, however, that hot water may also be introduced into the bagasse through the manifold 36, or through a separate manifold, or that other means such as a conveyor having a heated jacket, may be used for heating the bagasse. In accordance with the invention, the heated bagasse is discharged through the outlet 34 directly into the inlet 38 of a screw press 40 and is heated to a temperature preferably within the range of 180 F. to 200 F.

Preferably the screw press 40 is constructed in accordance with the disclosure of the copending application Ser. No. 283,518, filed May 27, 1963, now US. Patent No. 3,246,597, and which is assigned to the same assignce as the present invention. Generally this screw press includes a higher speed feed worm, as shown in said application which receives the bagasse from the inlet 38 and feeds it into the inlet of a barrel-like cage having a discharge outlet 47. The cage 45 supports a series of axially extending screen bars (FIG. 3) which are spaced apart to define slot-like drainage openings 52 therebetween and are annularly arranged to define a circular pressing chamber 54.

A main screw shaft 56 extends through the pressing chamber 54 and preferably has mounted thereon a series of worm members having spiral flights which may be interrupted by alternately spaced tapered collars, as is well known. The feed worm and the worm members are driven by an electrical motor 64 a turbine or other means through a gear reduction unit 65.

As illustrated in FIG. 2, the conveyor 28 along with the steam injecting manifold 36 are also adapted to be used in conjunction with a batch type or a continuous diffuser which is commonly used for extracting or removing sucrose bearing juices from sugar cane. Thus the bagasse which is discharged from the outlet 72 of the diffuser 70 is directed into the inlet 26 of the conveyor 28 for the same purpose as bagasse is delivered by the conveyor 24 from the final roller mill 20. In the case of batch type diffusers, a conveyor (not shown) may be employed to carry the bagasse from the diffuser to the inlet 26.

FIG. 4 shows another modification of the invention, in which sugar cane is fed from a conveyor 74 through a grinding means, such as a hammermill or shredder 75, and then passed to the inlet 26 of the conveying apparatus. Normally in such grinding means the cane material is torn or shredded without removal of much juice, although it is possible to have juice removed therein if desired. The material is then, as previously, heated substantially just before it is fed to the press, thereby obtaining the advantages of ease of pressing, power saving, and lessening of strain on the press.

As a result of heating the bagasse or cane material, it has been found that the material is softened and tends to become somewhat slippery, and it can be fed into and through the screw press 40 at the same capacity as previously, while requiring substantially less horsepower from the drive motor 64. For example, on one 600 horsepower press, it was determined that a reduction in horsepower of approximately 15% was achieved which is quite significant in view of the fact that it is common for the screw press to run continuously and that electrical or other power is usually expensive in areas where sugar refining plants are located. When material of this nature is heated, immediately before or as it is fed into the press, the fibers are softened and it has been found that the material is easier to press and presents less friction during working and compacting in the press. In addition, it has been observed that vibration in the press is appreciably reduced by heating the material as explained,

therefore additional benefit is achieved by lessening the strain and wear on the press mechanism.

While the foregoing specification discloses a preferred form of mechanical press, namely a screw press, it should be understood that other forms of continuous duty mechanical presses can be used.

While the processes herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise processes, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. An improved process for treating sugar cane material, comprising the steps of treating the material to expose the fibers, conveying the material towards the inlet of a mechanical press having substantial drainage openings and capable of sustaining pressure on the material, heating the material to at least F. by introducing hot fluid .into the material while conveying it toward said press, and immediately compressing the hot material in said mechanical press to express liquid therefrom such that the material is fed through said press with substantially less power and vibration.

2. A process as defined in claim 1 wherein the material is heated to within a temperature range of F. to 200 F. immediately before feeding the material into said inlet of said press.

3. An improved process for treating sugar cane material, comprising the steps of grinding the material to expose the fibers, conveying the material toward the inlet of a mechanical screw press having drainage openings, heating the material to at least 160 F. by introducing hot fluid into the material substantially the entire time the material is being conveyed toward said inlet, feeding the heated material directly and immediately into the inlet of said press, and compressing the heated material within said press to express liquid from the material through said drainage openings such that substantially less power is required for driving said press.

4. An improved process for treating sugar cane material, comprising the steps of passing the material through apparatus for removing sucrose-bearing juice, conveying the material from said apparatus toward the inlet of a mechanical screw press having rotatable screw flight means and drainage openings therein, heating the material to at least 160 F. by introducing hot fluid into the material while conveying the same toward said inlet, feeding the heated material into the inlet of said press, and compressing the heated material within said press to express liquid therefrom through said drainage openings such that substantially less power is required for rotating said screw flight means.

References Cited UNITED STATES PATENTS 641,266 1/1900 Bussells 100117 X 1,421,283 6/1922 Meakin 100--92 X 1,956,615 5/1934 Hansen 100-37 X 2,554,082 5/1951 Anderson 100147 X 3,067,672 12/1962 French 100-75 3,086,452 4/1963 French 100-75 3,093,064 6/1963 Burner et al. 100-37 FOREIGN PATENTS 166,527 8/ 1922 Great Britain.

LOUIS O. MAASSEL, Primary Examiner, 

